Electrical Problem? [Archive] - SaabCentral Forums

: Electrical Problem?


L0WRIDE
17th August 2008, 06:21 PM
Ok so I just finished rebuilding my engine and dropped it back in and I'm trying to get it going. I hooked everything back up and ended up putting in a new alternator and starter as well. Here's the problem...

It wouldn't crank at first and so I went and tightened the battery cables and it started to turn over... I figured it might take a few attempts considering all the new fluids would have to get back into the system.

I cranked it twice for about 15 sec each time and on the third time I got nothing? the oil light and other instrument lights are dim and nothing seems to be happening? no click, no crank, no nothing?

There's a small little black wire that connects from the oil dipstick to the drivers side wheel tub that looks like a ground of some sort? every time I would try to start it the wire became extremely hot and at one point smoked a little? why would that occur?

well were it stands now is everything seems to be hooked up correctly and I'm just getting dim instrument lights and no starts and not even the brake booster kicks in?

is there some kind of switch that tells when the clutch is depressed? I put in a new master cylinder for the clutch and was wondering if that had something to do with it?

I also have yet to align the gear shifter as well?

PLEASE HELP! I want to commit suicide at this point!

900t
17th August 2008, 06:34 PM
you have forgotten to install a ground between engine and body please do so immediately :lol:

L0WRIDE
17th August 2008, 10:25 PM
would this ground be anything different from the ground attached by the intake manifold? the mount used for removal? I have that attached?

AUSSIE900
17th August 2008, 11:24 PM
You Need One solid substantial ground between the engine and the body , Usually it will be under the head of a primary gears cover bolt and back to the main ground point .
You mat referring to the ground points for Injector wiring etc , but they are there with the assumption that the engine is already grounded .

Perhaps the one you have attached is to small , corroded , or broken .

Your symptons certainly fit 900T's advice ,

AUSSIE900
17th August 2008, 11:32 PM
Why the smoking occurs ...

That wire you described is doing its darndest to facilitate the *return* voltage , (negative) BUT try as it may ... it just aint up to it !! :cheesy: hence .. it overheats ..smokes... . Poor lil guy ... Took one for the team ..it tried to resist .. :lol:

Cables have amperage capacitors .. be they Positive or Neg . If the main ground isnt connected , current will always find another way ...
Its smart .. it will find the Path of least resistance .. BUT IT WILL follow a path ...

c900
18th August 2008, 12:25 AM
would this ground be anything different from the ground attached by the intake manifold? the mount used for removal? I have that attached?

There should be a very large ground cable (either a wide flat copper braid, or a large diameter round cable) connected between a bolt near the front of the transmission casing and the primary earth point behind the lower-right back corner of the radiator near the front engine mount.

If that's missing, you're going to have the starter motor trying to source a huge amount of current through very small (by comparison) earth connections elsewhere around the engine bay and that will most likely result in over-loaded small-diameter ground wiring.

Craig.

L0WRIDE
18th August 2008, 12:34 AM
PRAISE GOD! Thank you all very much for your help! sure enough I forgot to re-attach the main ground to the tranny. I was looking down at the main earth near the rad and plain as day there laid the unconnected cable.

Hooked it up and in fired right away! Thanks again!

AUSSIE900
18th August 2008, 01:38 AM
good stuff ... you need send 900t a Packet of Werthers ... :cheesy:

L0WRIDE
19th August 2008, 11:34 AM
So just when I thought that I had it fixed by attaching the ground to the trans (which it did start a few times and act normal) the little gremlins are back! I've checked and cleaned the earth near the rad, I've cleaned and sanded the spot on the trans, and now the dim lights are back and nothing is happening... it's just like before?!?!

Any other areas I should be looking at?

Jim Mesthene
19th August 2008, 11:51 AM
http://www.aa1car.com/library/voltage_drop_testing.htm

c900
19th August 2008, 05:40 PM
If the car has an auto transmission, it might be the neutral safety switch playing up. When you turn the key around to the 'start' position (which enables the 'terminal 50' circuit that supplies power to the starter solenoid), wiggle the transmission shifter back and forth gently when it's in 'P' and see if that makes any difference. If it does, you know what the culprit is. The sliding contacts inside the NSS assembly wear over time and don't always make good contact when the shifter sits resting naturally in 'P'.

If the car has a manual transmission, I am not sure if the reverse lockout feature would prevent the key turning to 'start' but that would possibly give a different symptom.

I'dbe double-checking all the primary power and ground connections, checking fuses, and also checking the battery terminal connections to make sure they aren't being impeded by a layer of crud/verdigree/etc. that is resulting in a significant contact resistance that prevents the starter being able to draw enough current from the battery.

The other thing to check is that the alternator is actually charging the battery. When the engine is running, you should be able to measure between 13.5 and 14.5 volts at the battery terminals. If not, the charging circuit isn't working properly.

Craig.

Rodentmaster
19th August 2008, 06:18 PM
http://www.aa1car.com/library/voltage_drop_testing.htm

Wow, That bought back memories of early electronics at high school. Some of those basics can really help any electrical diagnosis.

Good Link.
Top Stuff Jim

L0WRIDE
19th August 2008, 11:00 PM
great info! I'll read it over and give it a go in the morning! Thanks again!

L0WRIDE
20th August 2008, 01:40 PM
Well after searching with my DVM I found that my positive connection was lose and just needed tightening?! Well problem fixed and it runs like a charm! thanks for all the help!